British Prime Minister David Cameron is scheduled to chair a meeting of his government's crisis committee following some the worst street violence in English cities in decades.

Officials said Cameron was returning early from his holiday in Italy to lead the response to the looting and arson that late Monday had spread to at least four cities -- the capital London, Birmingham, Bristol and Liverpool.

Police say they have arrested more than 330 people in London, and about 100 in Birmingham. Police said 1,700 reinforcements had been called in to deal with gangs of rioters in London who clashed with police and looted in at least seven neighborhoods of the capital.

Reports say the rioters appear to have little unifying cause, but some involved in the unrest have cited cuts in government social services and sluggish economic growth.

The unrest began in London three days ago following a mass protest against the death of a man in a police shooting incident.